Radiation Spectra from Advection-dominated Accretion Flows in a Global Magnetic Field

We calculate the radiation spectra from advection-dominated accretion flows (ADAFs), taking into account the effects of a global magnetic field. Our calculation is based on the analytic model for magnetized ADAFs proposed by Kaburaki, in which a large-scale magnetic field controls the accretion process. Adjusting a few parameters, we find that our model can well reproduce the observed spectrum of Sagittarius A*. The result is discussed in comparison with those of well-known ADAF models, in which the turbulent viscosity controls the accretion process.